Fuel
cell basics

There are several
kinds of fuel cells, but in principle, every fuel cell operates
something like a battery. It will produce energy in the form
of electricity and heat as long as fuel is supplied.

A fuel
cell consists of two electrodes sandwiched around an electrolyte.
Oxygen passes over one electrode and hydrogen over the other,
generating electricity, water and heat. Hydrogen fuel is fed
into the “anode” of the fuel cell. Oxygen (or air)
enters the fuel cell through the cathode. Encouraged by a catalyst,
the hydrogen atom splits into a proton and an electron, which
take different paths to the cathode. The proton passes through
the electrolyte. The electrons create a separate current that
can be utilized before they return to the cathode to be reunited
with the hydrogen and oxygen in a molecule of water.

A fuel cell system
which includes a “fuel reformer” can
utilize the hydrogen from any hydrocarbon fuel – from
natural gas to methanol or even gasoline. Since the fuel cell
relies on chemistry and not combustion, emissions from this
type of a system would still be much smaller than emissions
from the cleanest fuel combustion processes.

This explanation
comes from Fuel Cells 2000, an online reference. See www.fuelcells.org.